Method for the electrolytic polishing of metal articles



169-45. XR 2.757. 136 SR I X fail? 31, J HEYES METHOD FOR THEELECTROLYTIC POLISHING 0F METAL ARTICLES Filed March :51. 1953 I HISAGENTS 2,757,135 Patented July 31, 1956 IVIETHOD FOR THE ELECTROLYTICPOLISHING OF METAL ARTICLES Josef Heyes, Dusscldorf-Obcrkassel, GermanyApplication March 31, 1953, Serial No. 345,939

3 Claims. (Cl. 204-1405) The invention relates to a device for theelectrolytical polishing of metal articles.

The use of an electrolyte based on acetic-acid-perchloric-acidpresupposes that an explosive decomposition of the mixture must beprevented by all means. A solution of one part of perchloric acid inthree parts of acetic acid is not explosive whereas this is the casewith a solution containing three parts of perchloric acid and one partof acetic acid.

It has been found that an explosive separation of an electrolyte of thenamed composition may not take place under ordinary operativeconditions; it becomes only possible, if in the case of a highly heatedor burning electrolyte a particularly intensive evaporation is causedwhich leads to steadily increasing accumulation of perchloric acid inthe mixture. lf a certain concentration of perchloric acid is exceededthe residual mixture will be decomposed in an explosive manner.

It ie fhP (\hipnt nf the inventing tr IIIQIII"? a eufn nea ofelectrolytes consisting of acetic acid and perchloric acid. whereby anydanger of-"explosion is eliminated.

Whereas an automatic interruption of the current supply at a time wherethe critical temperature of the electrolyte is reached, for instance, inthe case of fire, will be inefiective in view of the outer thermiceffects, which act upon the electrolyte, it was found that already asmall admixture of water to the electrolyte eliminates in the operativerooms the inflammation of the vapors which are produced by the heat. Inconformity with the above, water is added to the electrolyte consistingof acetic acid and perchloric acid as soon as a certain room temperatureis exceeded. This object may be realized by connecting a tube reachinginto the electrolyte to a water supply while interposing into the devicea so-called melting valve or safety fuse. With the known melting valvesor safety fuses the closure member consists of a low melting material.lf the melting temperature is exceeded water flows into the electrolyteand the danger of ignition is eliminated.

ln conformity with another characteristic element of the invention watermay be sprayed onto the bath surface from a tube with spray openings andlocated above the surface of the electrolyte.

Also in this case the tube may be connected with the water supply of aheat sensitive valve or the spray openings may be closed by a lowmelting material. The spray tube located above the bath and the tubeleading into the same may be connected to a common safety fuse.

lt has been found particularly effective to apply means which permit aquick removal of the electrolyte. With this purpose in view thecontainer for the electrolyte or its outlet means may be provided withan easily breale able, for instance. glass closure having a striking pinwith an interposed fusion strip suspended above the same.

The striking pin may be suspended to the one end of a rope conducted onrollers, whereas the other end of the rope is connected to a weightedlever. which closes a valve provided in the water supply, whe rebysafety fuses are provided in the rope between the water valve and thestriking pin.

It has been found advisable to additionally use a control relay which isadjusted to about 40 C. and to adjust the water supply valves to a roomtemperature of 60 to C.

The wall faces of the vessel containing the electrolyte are watercooled.

The installation is supported on a grate or the like in such a mannerthat the cooling water and eventually also the sluiced out electrolytemay be easily flown off.

The invention is by way of example illustrated in the accompanyingdrawings.

In the drawings Figs. 1 and 2 show longitudinal sections of the devicefor the electrolytical polishing of articles constructed in accordancewith the invention of the outlet from the vessel containing theelectrolyte, and i Fig. 3 shows a cross section of the outlet from thevessel containing the electrolyte.

The electrolyte 2 is contained in vessel 1; a thermometer 3 is providedfor. measuring the temperature of the electrolyte. If a certaintemperature of the electrolyte is exceeded the relay R interrupts thecurrent supply to the electrodes (not shown).

A tube 4 which is connected with a water supply reaches into theelectrolyte; a valve 5 is inserted into the water conduit.

The valve 5 is a so-called melt-valve, of which the closure elementconsists of a low melting metal such as Wood metal.

In addition to tube 4 a sluicing or spraying tube 6 is qr-nujdp lsl-want this Bl\lvffll\ll vt\ ris? m n n s 1 provided with aheat-dependent valve 8. In addition to valve 8 the openings 7 of thespraying tube by the closed means which melt of a certain temperature isexceeded. The tube 4 and the spraying tube 6 may be connected to onecommon valve.

In the modification of the invention shown in Fig. 2 the water supplytube 4 and the spraying tube 6 are operatively connected by means of acommon conduit 9 with the closure valve 11 located in the water supply10. Valve 11 is kept closed by a loaded lever 12. This lever isconnected to a rope 13, which runs over rollers 14 and causes at theother end a striking pin 15. Safety fuses 16, 17 are applied to therope.

The striking pin 15 acts upon the discharge socket 18 of the container 1containing the electrolyte. This dis charge socket is provided with aclosure 19 consisting of an easily breakable material, for instanceglass. As soon as the two safety fuses 16. 17 start to melt under theinfluence of an increased room-temperature not only the valve 11 isopened but the striking pin 15 drops and crushes the closure means 19 ofthe discharge socket 18. The electrolyte which is sprayed with water anddiluted may now quickly run-off from the vessel 1.

The closure 19 may be exchangeably connected with the socket 18 by meansof cap unit 20, see Fig. 3.

Since certain changes may be made in the above devices and differentembodiments of t. invention could be made without departing from thescope thereof. it is intended that all matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted asillustrative and not in a limiting sense.

What I claim is:

1. In a method for the electrolytical polishing of metal articles bymeans of an inflammable liquid electrolyte having a low ignition point,said articles being placed in a tank containing said electrolyte. thesteps of preventing the inflammation of the heated electrolyte byintroducing water through a tube into the bt ttom portion of the same,automatically controlling the supply of said water upon theestablishment of a certain predetermined temperature in the electrolyteand simultaneously removing the diluted electrolyte from said tank.

2. In a method for the electrolytical polishing of metal articles bymeans of an easily inflammable liquid electrolyte having a low ignitionpoint, said articles being placed in a tank containing said electrolyte,the steps of preventing the inflammation of the heated electrolyte byintroducing water through a tube into the bottom portion of the same,automatically controlling the supply of said water upon theestablishment of a certain predetermined minimum temperature in theelectrolyte and simultaneously removing the water-diluted electrolytefrom said tank by flowingvthe same over the upper rim of said tank.

3. In a method for the electrolytical polishing of metal articles bymeans of an easily inflammable liquid CliClfO lyte having a low ignitionpoint said articles being placed in a tank containing said electrolyte,the steps of preventing the intlammation of the heated electrolyte byintroducing water through a tube into the bottom portion 4 of the same,automatically controlling the supply 0 said water upon the establishmentof a certain predetermined minimum temperature in the electrolyte andsimultaneously removing the water-diluted electrolyte from the bottomportion of said tank by the automatically controlled opening of a tankexit.

References Cited in the file of this patent UNITED STATES PATENTS671,240 Shuman Apr. 2, 1901 1,260,818 Schultz Mar. 26, 1918 2,532,907Hangosky Dec. 5, 1950 FOREIGN PATENTS 205,181 Great Britain Oct. 11,1923 980,505 France Dec. 27, 1950 OTHER REFERENCES MetalFinishing,November" 1949, pages 62-68, article by Jacquet. The safe use ofperchloric acetic electropolishing baths.

1. IN A METHOD FOR THE ELECTROLYTICAL POLISHING OF METAL ARTICLES BYMEANS OF AN INFLAMMABLE LIQUID ELECTROLYTE HAVING A LOW IGNITION POINT,SAID ARTICLES BEING PLACED IN A TANK CONTAINING SAID ELECTROLYTE, THESTEPS OF PREVENTING THE INILAMMATION OF THE HEATED ELECTROLYTE BYINTRODUCING WATER THROUGH A TUBE INTO THE BOTTOM PROTION OF THE SAME,AUTOMATICALLY CONTROLLING THE SUPPLY OF SAID WATER UPON THEESTABLISHMENT OF A CERTAIN PREDETERMINED TEMPERATURE IN THE ELECTROLYTEAND SIMULTANEOUSLY REMOVING THE DILUTED ELECTROLYTE FROM SAID TANK.